1. Field of the Invention
The present invention relates to devices which transmit electrical energy from a stationary source to a moving device.
2. Description of the Related Art
A number of devices have been made which couple electrical energy from a transmitting terminal to a receiving terminal of an electrical device. This has been accomplished with relative ease in devices where both the source and receiving device remain stationary with respect to one another. For example, in one previous system, energy is radiated at high frequencies from a conductive plate proximate to a gaseous conduction tube. The energy radiated from the plate excites the gas within the tube so that the gas within the tube is illuminated.
In some electrical devices, however, it is desirable that electrical energy be transmitted from a stationary electrical source to a moving device. For example, in many electrical generators and motors it is necessary to couple electrical energy from a rotating device which carries electrical current to a stationary voltage output terminal. This is typically accomplished by means of conductive carbon brushes or the like interacting with a rotating ring or a commutator, for example. In this fashion, current generated by rotating a conductor through a magnetic field may be transmitted to a stationary electrical circuit.
However, it has been found that, in certain applications, disadvantages are associated with coupling electrical energy from a stationary source to a moveable device by means of a conductive contact (e.g., a brush or bearing). In particular, these conductive brushes create friction due to their physical contact with the rotating device. This friction results in a loss of energy, thereby reducing the efficiency of the system. In addition, the friction between the conductive contacts of the stationary source and the moving device create wear on both the contacts and the moving device. Thus, it may be necessary to replace those elements of the system which have suffered wear due to friction. Such replacement can often be inconvenient and costly.
Therefore, a need exists for a method and apparatus for coupling electrical energy from a stationary source to a moving device without creating a frictional contact between the source and the moving device.